1. Field of the Invention
This invention pertains to a slide for a sorting machine and more particularly to a slide for handling high volume products. The product to be sorted may include specimens with color defects or of irregular size or shape, or foreign objects.
2. Description of Prior Art
A typical sorting machine of the type using the present invention can be characterized as a gravity-fed channel sorter. Such a sorter incorporates a slide or chute at a steep angle having one or more channels across its width. A hopper or other feed system is positioned to dispense its product on the top of the slide. If multiple channels are used, the slide is divided across its width and configured so that an approximately evenly proportioned number of dispensed products are directed to each of the channels. Such techniques of distributing to each channel the proper amount of product being dispensed onto the slide is well-known in the art. A typical slide has numerous channels that may number as high as 64 or more, although slides for many machines in service today have only a limited number of channels, like 8, and in some applications it is preferable to use a single channel.
Gravity slide sorters have been in use for many years, sorting a wide variety of food products and many non-food products as well. Early sorters were single channel units, with a xe2x80x9cCxe2x80x9d-, xe2x80x9cUxe2x80x9d-, or xe2x80x9cVxe2x80x9d-shaped slide conveying product to a viewing area. Later, larger sorters were developed with 2, 6, 8, 12, etc., individual slides on a single frame. These individual slides were similar to the slides used on the single channel units, but economies were gained by constructing multiple slides on a single frame. These sorters presented multiple linear streams, or xe2x80x9cstringsxe2x80x9d, of product to be viewed.
In the early 1980xe2x80x2s, in response to the need for higher capacity sorters and to the need to sort products which would not flow smoothly down a slide, flat belt sorters were introduced. These sorters presented a wide sheet of product to the viewer.
In the mid-1980xe2x80x2s a type of sorter was introduced which combined the simplicity and space efficiency of the discreet channel sorter with the high throughput capability of the belt sorter. These xe2x80x9cbroad slidexe2x80x9d sorters presented multiple flat streams of product to the viewer. The total throughput of these multiple flat streams was often equal to the throughput of competing belt sorters. Early applications of this type of sorter were primarily in cereal grains such as rice. It has recently been demonstrated that this type of sorter can be applied to a variety of other products such as tree nuts, ground nuts, beans, etc., which had previously been sorted on smaller discreet slide sorters or on belt sorters. With this expansion of the application of broad slide sorters, several technical challenges have arisen concerning the design of the overall slide arrangement and the design of the configuration of each individual channel used on a broad slide sorter.
Successful sorters have been developed for cereal grains using wide, flat slides, which present a xe2x80x9csheetxe2x80x9d of product to the viewer/ejector system. This is similar to the product presentation of the belt sorter. Other successful sorters have been developed using slides that are also wide and flat, but in addition, have a series of dividing ribs separating the sheet of product into a series of xe2x80x9cribbonsxe2x80x9d of product, one per channel. These ribbons are presented to the viewer/ejector system oriented so that each ribbon passes in front of only one ejector. This important feature eliminates the condition of a defective product or article passing through the viewer in a location that causes two adjacent ejectors to fire at the same product, which often ejects an excessive amount of acceptable product along with the unacceptable. Logically, by eliminating the condition of product flowing through the zone of more than one ejector, a slide divided into channels, as just described, results in fewer total ejector fires and the removal of less good product. The innovation described below can be applied to both undivided and divided slide sorters, but the advantages of aligning ribbons of product flow with slide ejectors make the divided slide system more attractive in most applications. This difference is even more significant as the sorter is applied to products larger than cereal grains or to highly contaminated product flows.
The purpose of the slide is to accelerate and singulate the product, and to present it uniformly into the viewing area. For optimum sorting of certain types of products on slide chutes, it was discovered long ago that a product guide across the top of a chute was desirable to stabilize product flow in the chute of the slide sorter. Such a product guide is also known as a xe2x80x9ckeeperxe2x80x9d. Product guides have been used for many years to control bounce and tumbling on a slide and to knock down stacked product. Such a guide, usually a thin, flexible, plastic strip, is placed above the product flow. Conventionally, the width of the strip is selected so that it rests on the sides of the channel, or on the channel dividers, allowing the product to flow freely under it. The strip remains near the product so that if the product bounces up, or if product is riding one on top of another, the product is forced back down to flow evenly in the bottom of the channel. For most products, a product guide improves product flow.
Such slides have been used on a variety of products. However, a common problem with such slide arrangements is jamming or blocking of a channel. The obstructing object may be too large to enter the channel beneath the product guide, or, once in the channel, rotate to an orientation that causes it to become lodged. This can occur because of oversized product or large foreign objects.
A recent improvement to stabilize product flow when sorting larger products such as lentils or plastic flakes was to modify the height of certain dividing ribs of the chute. It has been found that the optimum channel configuration for many applications is to modify the dividing rib arrangement by reducing the height of every other rib. This modification allows the majority of the product flow to be controlled by the respective channels, as it would be if all ribs were in place, achieving the objective of oriented product flow so that each ribbon of product passes in front of only one ejector. However, if a large piece of product or a piece of foreign material or a misshaped product is fed into a channel, instead of being jammed in the channel and disrupting product flow, it can xe2x80x9coverflowxe2x80x9d into the adjacent channel and is passed through the sorter.
It is also known in the art that for round or oblong products, such as nuts and beans, the bottoms of the channels in the multiple channel slide, instead of being flat, generally should be rounded. For both the flat- and rounded-bottomed channels, the selection of a particular slide is determined by the size and shape of the product being sorted. The objective is to match the size of the channel to the size of the product so that it flows smoothly without excessive bounce, but is not slowed by running too tightly in a channel. Newer existing sorters, to optimize flow, use a channel profile matching the shape of the product being sorted in conjunction with interspersed dividing ribs of full height to support the product guide. Full or tall height dividing ribs occurring at every third divider rib position, or even less frequently, have been successfully used to support the product guide. While this improves (by reducing) the frequency of jams, jams still occur. Thus, the need exists for an improved arrangement in which fewer jams occur.
The present invention pertains to a slide for a gravity-fed sorting machine. The slide may be divided into multiple channels for separate viewing and ejection sorting action. The slide is positioned for use by being established at a large angle to the horizontal. Product to be sorted is deposited from a hopper or otherwise directed to the channel or various channels and to slide down them. Each channel may be flat- or round-bottomed, as desired, and is separately viewed in an electro-optical viewing station so that an ejector aligned with the channel and downstream from the viewing station fires to remove nonstandard or defective products or other objects. The dividing ribs between channels, when present, are at least as high as to ordinarily keep the products from transferring from one channel to the next. The dividing ribs may be of different heights. A product guide or keeper is supported across the top of the slide to prevent products from excessive bouncing or xe2x80x9cpiggybackxe2x80x9d stacking.
An optimum gravity slide configuration comprises one or more channels, with or without dividing ribs, and a product guide. An improvement in product control is achieved by exploiting a new product guide design. The product guide itself is modified to have support tabs integral to or otherwise extending from its perimeter. Those tabs allow the product guide to be supported by support brackets, as explained below, while retaining certain degrees of freedom regarding its ability to move. Specifically, the tabs rest in notches in the underlying support brackets that allow the product guide to be lifted up, thus permitting a potential obstruction to pass. Additionally, the brackets themselves are adjustably mounted to the sides of the slide. That allows the product guide""s height above the channel bottom or dividing ribs to be varied to provide a clearance to best accommodate the particular product being sorted.